Zein, shellac and other materials have been used as encapsulating agents for high intensity sweeteners. The term "high intensity sweeteners" is defined herein to include sugarless sweeteners having a degree or intensity of sweetness which is many times greater than sucrose. High intensity sweeteners include, but are not necessarily limited to, aspartame, sucralose, salts of acesulfame, alitame, glycyrrhizin, saccharin and its salts, cyclamic acid and its salts, dihydrochalcones, thaumatin, monellin and the like, alone or in combination.
High intensity sweeteners benefit from or require encapsulation in order to achieve a gradual and controlled release of sweetener during chewing and/or to promote their stability in chewing gum. For example, certain artificial dipeptide sweeteners such as aspartame (L-aspartyl-L-phenylanaline methyl ester) have been found to be excellent sugar substitutes in chewing gum. However, the stability of artificial dipeptide sweeteners depends on exposure to moisture, time, temperature and pH. Under unfavorable conditions, aspartame spontaneously converts to diketopiperazine with proportional loss of sweetness. Aspartame also degrades when exposed to aldehyde-type flavoring agents. In order to maintain the stability and sweetness of aspartame in chewing gum, it is necessary to minimize the exposure of aspartame to moisture, aldehyde-type flavors, and certain pH conditions.
Zein, shellac and many other materials have been used to encapsulate aspartame and other high intensity sweeteners, in order to control the stabilities and rates of release of the sweeteners. For instance, U.S. Pat. No. 4,673,577 discloses the use of shellac, individually, to encapsulate high intensity sweeteners. U.S. Pat. No. 4,863,745 discloses the use of zein to coat high intensity sweeteners which have already been once coated with another material. The previous coating can be shellac.
U.S. Pat. No. 4,931,295 discloses the coating of aspartame and other high intensity sweeteners with a mixture of zein and hydroxypropylmethyl cellulose. U.S. Pat. No. 4,384,004 discloses several coating materials for aspartame, including zein. PCT Publication WO 90/06061 discloses the use of equal amounts of zein and shellac mixed together, to coat alitame.
European Patent Application No. 0 320 523 discloses the use of zein, shellac and other materials to agglomerate high intensity sweetener particles in a solvent. U.S. Pat. Nos. 4,122,195 and 4,139,639 disclose the fixation of aspartame in reaction product of a compound containing a polyvalent metal ion, with an ungelatinized starch acid-ester of a substituted dicarboxylic acid. U.S. Pat. No. 4,386,106 discloses an encapsulant for a flavoring material, composed of gelatin, a natural gum and a plasticizer. U.S. Pat. No. 4,485,118 discloses the use of shellac to encapsulate a flavoring material.
U.S. Pat. No. 4,590,075 discloses an elastomer system for encapsulating flavor and sweetening agents. U.S. Pat. No. 4,722,845 discloses the encapsulation of dipeptide and amino acid sweeteners in a mixture of fat and polyethylene wax. U.S. Pat. No. 3,116,206 discloses generally the use of zein as an encapsulant.